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Dye-Sensitized Solar Cells Using Fresh and Dried Natural Dyes
Sofyan A. Taya,
Taher M. El-Agez,
Hatem S. El-Ghamri,
Monzir S. Abdel-Latif
Issue:
Volume 2, Issue 2, March 2013
Pages:
37-42
Abstract: Different natural dye extracts have been prepared and used as sensitizers in the fabrication of dye-sensitized solar cells (DSSCs). These dyes have been extracted from both fresh and dried raw materials. The absorption spectra of these dyes have been investigated by UV-VIS spectrophotometry. DSSCs were assembled using TiO2 and ZnO nanostruc-tured, mesoporous films. Photovoltaic parameters such as short circuit current density Jsc, open circuit voltage Voc, fill fac-tor FF, and overall conversion efficiency η for the fabricated cells were determined under 100 mW/cm2 illumination. The immersion time of the nanocrystalline-TiO2 electrode in spinach extract and the temperature at which this process occurs were optimized. The optimal dying temperature is found to be 60 °C and the efficiency of the DSSC is found to saturate to 0.29% after 12 hr of soaking in the dye solution.
Abstract: Different natural dye extracts have been prepared and used as sensitizers in the fabrication of dye-sensitized solar cells (DSSCs). These dyes have been extracted from both fresh and dried raw materials. The absorption spectra of these dyes have been investigated by UV-VIS spectrophotometry. DSSCs were assembled using TiO2 and ZnO nanostruc-tured, ...
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Optoelectronic Properties of Improved GaN Semiconductor on Si(111) Using Growth Approaches And Different Interlayer’s
Bablu K. Ghosh,
Ismail Saad,
Akio Yamamoto
Issue:
Volume 2, Issue 2, March 2013
Pages:
43-46
Abstract: The crystalline quality of wider direct band gap semiconductor (3.4 eV) hexagonalGaN(h-GaN)epilayer grown on Si(111) is evaluated by using different growth approaches and interlayer’s. The investigations of GaNepilayer crystal quality for the template of converted porous GaN layer formed by novel nitridation process of thin (2 and 0.5μm) GaAs layer on Si(111) and on C+ ion implanted very thin SiC layer formed on Si(111) and grown ambient effect are made. Epilayer grown on thinner non-isoelectronic converted SiC templates is found to broaden its PL line width whereas epilayer grown on porously converted GaN layer fromed from iso- electronic GaAs (111) layer on Si(111) is found narrow line width. H2 ambient grown film better crystalline quality and higher PL Ex. peak energy is found as compared to N2 ambient grown film. Low temperature PL measurement, similarity between defect related donor-acceptor peaks (DAP) to defect related yellow band luminescence at the room temperature PL measurement is also found. Grown epilayer different characterization reveals better crystalline quality h-GaN is achieved by using thin iso-electronic GaAS interlayer on Si(111) with H2 grown ambient.
Abstract: The crystalline quality of wider direct band gap semiconductor (3.4 eV) hexagonalGaN(h-GaN)epilayer grown on Si(111) is evaluated by using different growth approaches and interlayer’s. The investigations of GaNepilayer crystal quality for the template of converted porous GaN layer formed by novel nitridation process of thin (2 and 0.5μm) GaAs laye...
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A GTEM Chamber Design with Frequency Flexibility Using Metamaterial Concepts on the Septum
Humberto X. Araujo,
Humberto X. Araujo,
Luiz Carlos Kretly
Issue:
Volume 2, Issue 2, March 2013
Pages:
47-55
Abstract: In this work it is shown the strategy of use metamaterial technology to improve the GTEM chamber performance. The analysis and characterization of different types of metamaterial patterns, such as fractal cells, Jerusalem-Cross-Pair, SRR – Split Ring Resonator and CSRR – Complementary Split Ring Resonator printed on the septum of a GTEM chamber was done. The main goal is to give a flexibility frequency range for electromagnetic compatibility analysis of integrated circuits and electronic boards. Experimental results are compared to simulated ones showing the advantages of the tuned characteristic of the patterned septum in comparison to the conventional type. This technique appears as an option for the performance optimizations of compact GTEM chambers.
Abstract: In this work it is shown the strategy of use metamaterial technology to improve the GTEM chamber performance. The analysis and characterization of different types of metamaterial patterns, such as fractal cells, Jerusalem-Cross-Pair, SRR – Split Ring Resonator and CSRR – Complementary Split Ring Resonator printed on the septum of a GTEM chamber was...
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Effect of Cryogenic Treatment on Microstructure and Wear Characteristics of AISI M35 HSS
D. Candane,
N. Alagumurthi,
K. Palaniradja
Issue:
Volume 2, Issue 2, March 2013
Pages:
56-60
Abstract: Cryogenic treatment has been widely acknowledged as a means of improving wear resistance of tool materials. A Comparative study on conventionally heat treated and cryogenic treated AISI M35 grade high-speed steel specimens has been presented in this paper. Specimens initially subjected to conventional heat treatment at austenitizing temperature of 1200 ̊C were subsequently subjected to shallow cryogenic treatment at -84 ̊C for 8 hours and deep cryogenic treatment at –195 ̊C for 24 hours followed by double tempering at 200˚C. Presence of retained austenite was studied at the end of each of the above treatment using XRD analyzer. An estimated 19% retained austenite present at the end of conventional heat treatment was reduced to 5% at the end of shallow cryogenic treatment, while deep cryogenic treatment practically removed all traces of austenite in the sample. Changes in the microstructure were studied using SEM. Fine precipitates of carbides of size 0.3-0.5µ were observed in cryogenically treated samples. Variation in mechanical properties such as toughness and hardness has been studied. There was no change in toughness due to cryogenic treatment and it corroborates well with the results of fractography. Wear characteristics were studied using pin on disc wear tester. The operative modes and mechanisms of wear have been identified as severe delaminative and mild oxidative from the morphology of worn surface of pin. The results unambiguously confirm enhancement in hardness and wear resistance of cryogenically treated specimens.
Abstract: Cryogenic treatment has been widely acknowledged as a means of improving wear resistance of tool materials. A Comparative study on conventionally heat treated and cryogenic treated AISI M35 grade high-speed steel specimens has been presented in this paper. Specimens initially subjected to conventional heat treatment at austenitizing temperature of ...
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Love Wave Propagation in Electro-Magneto Non-Homogeneous Elastic Media
Shikha Kakar,
Rajneesh Kakar
Issue:
Volume 2, Issue 2, March 2013
Pages:
61-67
Abstract: A mathematical approach is taken to investigate Love wave propagation in non-homogeneous electro-magneto-elastic media. The elastic media is assumed to be initially unstressed and at rest. In this study, it is assumed that mass density , elastic coefficients , dielectric coefficients magnetic permeability coefficients , piezoe-lectric coefficients piezomagnetic coefficients and magneto-electric coefficients of the specimen are space dependent. The analytical solution for dispersion of love waves is obtained for electromagnetically short and open case. It has been shown that non-homogeneity factor reduces the penetration depth of Love waves. The numerically results are shown graphically.
Abstract: A mathematical approach is taken to investigate Love wave propagation in non-homogeneous electro-magneto-elastic media. The elastic media is assumed to be initially unstressed and at rest. In this study, it is assumed that mass density , elastic coefficients , dielectric coefficients magnetic permeability coefficients , piezoe-lectric coefficient...
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Electrocodeposition and Characterization of Ni-WC Composite Coating From Non – Aqueous Bath
Dhananjay kumar Singh,
Manoj Kumar Tripathi,
V. B. Singh
Issue:
Volume 2, Issue 2, March 2013
Pages:
68-73
Published:
10 January 2013
Abstract: Composite coating of tungsten carbide (WC) in the matrix of nickel has been achieved by direct current (DC) electrodeposition technique using a non aqueous bath. The deposition parameters such as current density, bath temperature, and stirring rate were maintained at constant levels for all the coating configurations. The composition of the coating and its microstructure were studied using energy dispersive x-ray spectroscopy, uv-vis spectrophotometry and x-ray diffraction, respectively. Surface morphology of the coatings was studied by scanning electron microscopy (SEM and TEM). Effect of heat treatment on the deposits microstructures and microhardness was also investigated. The Ni–WC composites, prepared at optimum conditions, exhibited improved mechanical properties in comparison to pure nickel electrodeposits.
Abstract: Composite coating of tungsten carbide (WC) in the matrix of nickel has been achieved by direct current (DC) electrodeposition technique using a non aqueous bath. The deposition parameters such as current density, bath temperature, and stirring rate were maintained at constant levels for all the coating configurations. The composition of the coating...
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Zno Nano-Stripes Synthesized using Photoelectrochemical Wet Etching Method
L. S. Chuah,
Asmiet Ramizy,
M. A. Mahdi,
Z. Hassan
Issue:
Volume 2, Issue 2, March 2013
Pages:
74-77
Abstract: To date, no approaches have been reported to fabricate the ZnO nano-stripes arrays on zinc foil substrate. In this method, zinc (Zn) foil was applied as substrates. The ZnO nano-stripes arrays on zinc foil substrate were prepared via photoelectrochemical (PEC) wet etching method without using templates and catalysts. To prepare ZnO nano-stripes structures, the samples were dipped into a mixture of HNO3:Ethanol (1:5) with current densities of 127 mA/cm2, and subjected to external illumination from a 100W lamp. The constant etch time is 30 min. After etching, the surface morphology and the nano-stripes structure of the ZnO films were characterized by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). XRD pattern confirmed that the hexagonal wurtzite structure of ZnO nano-stripes were of polycrystalline structure. The optical properties of the ZnO nano-stripes arrays were characterized by Raman and photoluminescence spectroscopies at room temperature (RT). Micro-Raman results showed that A1(LO) of hexagonal ZnO nano-stripes have been observed at 520 cm-1. PL spectrum peak is obvious at 368 cm-1 for ZnO film grown on zinc foil substrate. The PL spectrum peak position in ZnO nano-stripe is blue-shifted with respect to that in unstrained ZnO bulk (381nm). This can be clarified by the approximately smaller statistical area spreading of the nano-stripes. Nano-stripes ZnO can be used as a buffer or intermediate layer to lessen substrate-induced strain, similar to porous silicon.
Abstract: To date, no approaches have been reported to fabricate the ZnO nano-stripes arrays on zinc foil substrate. In this method, zinc (Zn) foil was applied as substrates. The ZnO nano-stripes arrays on zinc foil substrate were prepared via photoelectrochemical (PEC) wet etching method without using templates and catalysts. To prepare ZnO nano-stripes ...
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